Scripts Essay Research Paper 30

Scripts Essay, Research Paper

3.0 Variables

Scripts may contain variables. Variable names must begin with a letter or an underscore (’_'), and may contain any sequence of upper- or lower-case letters, digits, and underscores. You cannot use a reserved word as a variable name. For more information, see the list of reserved words at the end of this document.

You must declare variables before you use them. When you declare a variable, you must also define its type. A variable of a certain type may only contain values of that same type. The following three types of variables are supported:

Type Description

integer A negative or positive number, such as 7, -12, or 5698.

string A series of characters enclosed in double-quotes; for example, “Hello world!” or “Enter password:”.

boolean A logical boolean value of TRUE or FALSE.

Variables are assigned values using the following assignment statement:

variable = expression

The variable gets the evaluated expression.

Examples:

integer count = 5

integer timeout = (4 * 3)

integer i

boolean bDone = FALSE

string szIP = (getip 2)

set ipaddr szIP

3.1 System Variables

System variables are set by scripting commands or are determined by the information your enter when you set up a Dial-Up Networking connection. System variables are read-only, which means they cannot be changed within the script. The system variables are:

Name Type Description

$USERID String The user identification for the current connection. This variable is

the value of the user name specified in the Dial-Up Networking

Connect To dialog box.

$PASSWORD String The password for the current connection. This variable is the

value of the user name specified in the Dial-Up Networking

Connect To dialog box.

$SUCCESS Boolean This variable is set by certain commands to indicate whether or not the command succeeded. A script can make

decisions based upon the value of this variable.

$FAILURE Boolean This variable is set by certain commands to indicate

whether or not the command failed. A script can make decisions

based upon the value of this variable.

These variables may be used wherever an expression of a similar type is used. For example,

transmit $USERID

is a valid command because $USERID is a variable of type string.

4.0 String Literals

Scripting for Dial-Up Networking supports escape sequences and caret translations, as described below.

String Literal Description

^char Caret translation

If char is a value between ‘@’ and ‘_’, the character sequence is translated into a single-byte value between 0 and 31. For example, ^M is converted to a carriage return.

If char is a value between a and z, the character sequence is translated into a single-byte value between 1 and 26.

If char is any other value, the character sequence is not specially treated.

Carriage return

Linefeed

\” Double-quote

\^ Single caret

\< Single ' = Relational Integers

== != Equality Integers, strings, booleans

and Logical AND Booleans

or Logical OR Booleans

Examples:

count = 3 + 5 * 40

transmit “Hello” + ” there”

delay 24 / (7 – 1)